| Summary: | 碩士 === 國立臺灣大學 === 高分子科學與工程學研究所 === 101 === Two types of waterborne biodegradable polyurethane (WBDPU) in the form of homogeneous nanoparticles (NPs) were synthesized using biodegradable polyesters as soft segment. The first WBDPU (PU01) was based on polycaprolactone diol (PCL diol, Mw 2000) and the second WBDPU (PU02) was based on 40% PCL diol and 60% polyethylene butylene adipate diol (PEB diol, Mw 2000). The dispersion of WBDPU NPs were prepared in different solid contents, sprayed into liquid nitrogen, and resuspended in water. During the process, the NPs were self-assembled into microspheres, with an average size of 50-60 um. By adjusting the contents of NPs, microspheres could be obtained with different porosity. In vitro degradation results revealed that microspheres from PU02 (i.e. PU02 MS) has faster degradation rate than those from PU01 (PU01 MS). The release of methylene blue encapsulated during MS formation was investigated. PU02 MS made from 10% dispersion (i.e. PU02 MS_10) showed a greater burst release at 6 hours, whereas PU01 MS_30 had significantly lower burst release. Biocompatibility evaluation using L929 fibroblasts demonstrated that cells could attach on the microspheres after 24 hours. On the other hand, the microspheres may self-assemble further into films and scaffolds. The mechanical properties of self-assembled solid films from microspheres were similar to those from NP dispersion. Surface modification of microspheres by low molecular weight positively charged chitosan may modify the self-assembly behavior of microspheres. Scaffolds made of microspheres may have different porous structure by controlling the amount of microspheres that built up the scaffolds. Fibroblasts were successfully seeded and grown in the scaffolds. We concluded that the biodegradable and elastic microspheres with potential applications in drug release and cell carriers may be facilely produced from a green and sustainable process.
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